Radius arm and Panhard bar tech

[Stomis]

So Im beginning to plan the SAS in more detail for my trooper. Ive got down pat how Im gonna build my radius arms but one thing Im curious on is their mounting location in relation to the axle end.

Does it make a difference how far they are from the axle center line? I know the short tube is pretty much gonna dictate this but I was just curious

Also for a panhard bar what should I use? Heims? Size?

Aim for it to start on the driver side frame and end on the axle at the same location under the passenger side?

 

[cybrfire]

So Im beginning to plan the SAS in more detail for my trooper. Ive got down pat how Im gonna build my radius arms but one thing Im curious on is their mounting location in relation to the axle end.

Do you have an example of what you're radius arms will look like?

 

[Stomis]

Do you have an example of what you're radius arms will look like?

Early bronco clamps/wedges with the rods cut off. Some DOM slotted and welded into the ends, then plated with johnny joints on the frame end.

I had planned on making them straight with no kink/bend seeing as how Im only running 33s.

 

[cybrfire]

Aren't the ends fixed in relation to each other and the centerline of the axle with the Ford clamp style?

Sorry, I've seen the ford ones but its been a while.

 

[Stomis]

Aren't the ends fixed in relation to each other and the centerline of the axle with the Ford clamp style?

Sorry, I've seen the ford ones but its been a while.

Well seeing as how Im putting the wedges on a chevy axle I could put them where ever I want.

 

[folkenheath]

If you are using a Chevy axle and building from scratch I wouldn't use the ford ends. You can build your own easier out of bushing kits that will work better than the ford clamps and this allows you to not only pick your bushing seperation, but also allows you to make it wristed easier. If you are using bushings, the further vertical seperation of the bushnigs, the more axle control you will have but it will bind in articulation more (which the wristed option will eliminate). Now, if you put them closer together then you will have less control of axle wrap, but less bind. You can also use a combination of a spherical joint on the lower and a bushing on the upper, allowing you to leave the links closer together and still have axle control.

I ended up going with poly bushings top and bottom with a large spherical joint at the frame end, and I would have to measure, I don't remembed if I ended up at 7" or 8" vertical seperation.

As far as the width at the frame end, the wider they are the more control you will have with less stress on all the joints, but too wide and you limit your turning radius because the tires will hit the arm. So I would make it as wide as you can and still clear all the steering and tires at full lock.

Keep in mind on the axle end, the longer and lower the arms are at the frame, the less angle change (and therefore bind) there will be at the axle end for the same articulation angle. Also, moving the arms in at the frame end will reduce bind as well (in addition to increasing turning clearance), but if you go in too far you may sacrifice some control and handling as it will approach being a 1 link as the arms get close to the same point as you bring them together.

I used a 7/8 heim on the axle end of my panhard bar (for space limitations), and a spherical joint on the frame end with 5/8" bolts. My panhard bar is made out of 1.25" x 1/4" wall DOM so I could have it tapped for the ends. But mine is straight, if it needs to be bent you should probably step up to 1 3/8 or 1.5" DOM.

 

[ktmoutfront]

Or go with a three bar link with a panhard bar. All kinds of twisty with zero binding. My coil overs are what limit articulation. Should have leaned them in more. Also, the pan hard bar needs to be as long and level as you can make it. It should parallel the steering arm and be the same length. If not, bump steer will be bad.

 

[blazinzuk]

Don't talk yourself out of a basic 3 link just cause someone said its a little harder to design, its not.

While I have seen plenty of radius arms work and work very well. I have seen 3 links that work just as well but you can adjust somewhat to suit your driving needs.

I like the additional control you can gain by going to a true 3 link ( 2 lowers one upper), true its a bit harder to package and I have no clue what your frame looks like.

Not suspension control, control over ride characteristics. Radius arm you got what you got, the 3 link can benefit from tweaks and sometimes the illusive demon tweak is just a hole or an extra inch away

 

[Stomis]

If you are using a Chevy axle and building from scratch I wouldn't use the ford ends. You can build your own easier out of bushing kits that will work better than the ford clamps and this allows you to not only pick your bushing seperation, but also allows you to make it wristed easier. If you are using bushings, the further vertical seperation of the bushnigs, the more axle control you will have but it will bind in articulation more (which the wristed option will eliminate). Now, if you put them closer together then you will have less control of axle wrap, but less bind. You can also use a combination of a spherical joint on the lower and a bushing on the upper, allowing you to leave the links closer together and still have axle control.

I ended up going with poly bushings top and bottom with a large spherical joint at the frame end, and I would have to measure, I don't remembed if I ended up at 7" or 8" vertical seperation.

As far as the width at the frame end, the wider they are the more control you will have with less stress on all the joints, but too wide and you limit your turning radius because the tires will hit the arm. So I would make it as wide as you can and still clear all the steering and tires at full lock.

Keep in mind on the axle end, the longer and lower the arms are at the frame, the less angle change (and therefore bind) there will be at the axle end for the same articulation angle. Also, moving the arms in at the frame end will reduce bind as well (in addition to increasing turning clearance), but if you go in too far you may sacrifice some control and handling as it will approach being a 1 link as the arms get close to the same point as you bring them together.

I used a 7/8 heim on the axle end of my panhard bar (for space limitations), and a spherical joint on the frame end with 5/8" bolts. My panhard bar is made out of 1.25" x 1/4" wall DOM so I could have it tapped for the ends. But mine is straight, if it needs to be bent you should probably step up to 1 3/8 or 1.5" DOM.

Thanks thats the first real radius arm tech Ive been able to find. Guys on pirate just go "Eh you're using radius arms? just throw em on there it wont matter unless you go 3 link"


Theres a few reasons I decided to do it the way I am. At first I was planning on building custom radius arms with bushings and a straight "wristed" link on the other side. Then I decided that since street driving was more important than being super flexy that I would do standard radius arms on both sides for more sway control.

Then I started pricing out all the bushings kits and realized that it would be much cheaper to go with built ford arms and wedges. Plus this gives me the ability to mount the coils just like an early bronco on the wedge and the saving started adding up to over a couple hundred dollars between brackets, 6 bushing kits, more DOM, etc.

The reason I decided to do radius arms isnt because I doubt myself on doing a 3 link its because ive seen what it takes to do a 3 link on a trooper and keep it low and its not worth it to me.

 

[blazinzuk]

No matter how you build a radius arm it binds, the key is getting it not too bind in the range of motion you want. Your design should be dictated by this. If you can't get the range of motion in the parameters allowed without major binding then you need to rework or rethink your parameters or your design.

You can actually use the bind to stops suspension travel although this is hard on your components. Hence the reason you don't want hard bind in your intended range of travel. If the bind occurs on a regular basis you will wear out suspension components

It is certainly easier to package than a 3 link on just about anything

 

[folkenheath]

Thanks thats the first real radius arm tech Ive been able to find. Guys on pirate just go "Eh you're using radius arms? just throw em on there it wont matter unless you go 3 link"

I think too many people get caught up in the theory of the binding and just won't use radius arms, but the fact is they can work excellent when properly built, and if you wrist it, one bolt or pin removed basically makes it a 3 link with a fixed IC.

These guys are right, I don't disagree, a 3 link has zero bind when built right, and should have more flex than a non-wristed radius arm, but I haven't found the bind to be a problem for the wheeling I do, and the bind is removed as easy as one bolt.

I play a lot in the sand and some snow, along with dirt, hills, etc, I like horsepower and acceleration, I was not willing to give up my long tube headers for a standard 3 link, and if I did an inverted 3 link then I would need the upper arms outside the frame which would reduce my turning radius. Radius arms would not affect either of those, so I went with them, and I don't regret it. I have only taken the wristed bolt out once, just to see how it did at Bundy offroad park, but for the wheeling I do I couldn't tell a difference. With my setup the dual rate springs were limiting the articulation before the bushing bind was doing anything. Maybe if you had it setup with super soft springs the entire travel then it might limit you more, but you could still remove the wrist bolt.

Also keep in mind the longer the arm the less roll steer you will have. Basically, make the arms as long and low as possible on the frame side, because you'll run into ground clearance or vehicle interference issues before they would ever be too long or low.

From your description of use I don't think you will regret a radius arm if you build them right. But if you built it with short arms with no way for them to twist radially at the frame end, and have them angled way up to the frame, then maybe you won't like them. I am sure you can do it right either way, radius arm or 3 link.

 

[Stomis]

I think too many people get caught up in the theory of the binding and just won't use radius arms, but the fact is they can work excellent when properly built, and if you wrist it, one bolt or pin removed basically makes it a 3 link with a fixed IC.

These guys are right, I don't disagree, a 3 link has zero bind when built right, and should have more flex than a non-wristed radius arm, but I haven't found the bind to be a problem for the wheeling I do, and the bind is removed as easy as one bolt.

I play a lot in the sand and some snow, along with dirt, hills, etc, I like horsepower and acceleration, I was not willing to give up my long tube headers for a standard 3 link, and if I did an inverted 3 link then I would need the upper arms outside the frame which would reduce my turning radius. Radius arms would not affect either of those, so I went with them, and I don't regret it. I have only taken the wristed bolt out once, just to see how it did at Bundy offroad park, but for the wheeling I do I couldn't tell a difference. With my setup the dual rate springs were limiting the articulation before the bushing bind was doing anything. Maybe if you had it setup with super soft springs the entire travel then it might limit you more, but you could still remove the wrist bolt.

Also keep in mind the longer the arm the less roll steer you will have. Basically, make the arms as long and low as possible on the frame side, because you'll run into ground clearance or vehicle interference issues before they would ever be too long or low.

From your description of use I don't think you will regret a radius arm if you build them right. But if you built it with short arms with no way for them to twist radially at the frame end, and have them angled way up to the frame, then maybe you won't like them. I am sure you can do it right either way, radius arm or 3 link.

With how low my truck sits the height thing really isnt an issue. I plan on making them ago all the way to the back of the front door. So very extended just like the aftermarket arms for rangers, explorers, and broncos.

 

[97flexy]

I found this thread from a search of radius arm swaps, does anyone know if the OP ever finished his swap? I'm swapping in full size axles use'n ford radius arms like he talks about.

 

[Stomis]

You can check out my build thread in the driveway section. My front suspension is done.

 

[97flexy]

You can check out my build thread in the driveway section. My front suspension is done.

Cool! looking forward to reading it!!! I'm building my trac bar for the front and I'l be done, later this week I should have the back sitting on its own weight too.